JP2009051590A - Paper feeding device and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of an action failure such as a driven failure in a separating roll for separating recording sheets one by one, to prevent the occurrence of jamming of the recording sheets due to the action failure of the separating roll, and to suppress partial wear when a friction coefficient of a separating roll surface is lowered. <P>SOLUTION: The paper feeding device comprises a feeding roll feeding the plurality of stacked recording sheets; a carrying roll carrying only one recording sheet on a surface side of the recording sheets fed by the feeding roll; the separating roll arranged while abutting on the carrying roll, and separating the second or more recording sheets positioned on a back surface side from the first recording, when the feeding roll feeds two or more recording sheets; a separating roll rotation detecting means detecting a rotation state of the separating roll; and a determining means determining whether the recording sheets are normally separated or not according to a detection result of the separating roll rotation detecting means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a paper feeding device and an image forming apparatus using the same.

JP-A-61-106339 JP 62-004140 A Japanese Patent Laid-Open No. 03-026627 JP 2000-044076 A JP 2003-242530 A

  Conventionally, as the technology relating to the above-described paper feeding device, for example, JP-A-61-106339, JP-A-62-004140, JP-A-03-026627, JP-A-2000-44076, JP-A-2003. The technology disclosed in Japanese Patent No. 242530 has been proposed.

  The paper feed mechanism according to the above-mentioned Japanese Patent Application Laid-Open No. 61-106339 is provided on a transport path with a paper feed base for loading forms, a transport means for sending out the forms stacked on the paper feed base one by one. Detecting means for detecting that a plurality of sheets are fed every time, and when the plurality of feeds are detected by the detecting means, the conveying means is driven in a direction opposite to the sheet feeding direction so that the plurality of forms are transferred to the sheet feeding table. Means for returning to the top, and pressure adjusting means for appropriately adjusting the pressure exerted on the form of the conveying means so that the form is conveyed one by one after the plurality of forms are returned in the reverse direction by the means. It is comprised so that it may comprise.

  Further, an electronic copying machine according to the above-mentioned Japanese Patent Application Laid-Open No. 62-4140 is an electronic copying machine having a copy paper cassette that is detachably mounted on the side surface of the main body of the electronic copying machine. A lid that is pivotably hinged to the protruding side and covers the upper surface of the cassette is provided.

  Further, the electronic copying machine according to Japanese Patent Laid-Open No. 62-4140 is in pressure contact with a lever that pushes up a copy sheet at the cassette mounting position of the main body at the time of a copy operation, and a sheet positioned at the uppermost position. A pressure roller that rotates in the paper feed direction, a paper feed roller that is positioned at the front end of the pressure roller in the paper feed direction, and that rotates in synchronization with the pressure roller, a pinch roller that presses against the paper feed roller and rotates in the paper feed direction, A friction mechanism between the pinch roller and the paper is detected and a reverse mechanism is provided to reverse the pinch roller when there are multiple sheets sandwiched between the paper feed roller and the pinch roller. Is also pushed back into the cassette so that only one sheet passes between the rollers.

  In addition, the paper feeding control method in the paper feeding device according to the above-mentioned Japanese Patent Laid-Open No. 3-26627 includes a paper feeding unit provided with a pick roller that press-fits the paper and forms to the stacked body in order to sequentially feed the paper and forms from the stacked body. And a paper separating unit having a torque limiter having a variable limit torque for separating and feeding out the fed sheets and forms one by one and a separating rolling element for rolling engagement with the limiter. In the paper feeding control method of the paper feeding device provided with two paper position detection sensors for detecting the position and amount of the paper and forms, the paper position detection sensor detects slip and double feed of the paper and forms. Based on the detection information, the voltage applied to the torque limiter is controlled to change the limit torque, so that paper can be fed without slip or double feed. It is obtained by the.

  Further, the sheet medium separating apparatus according to the above Japanese Patent Laid-Open No. 2000-44076 discloses a sheet feeding unit that can be loaded in a state in which a plurality of sheet media are stacked, and a sheet medium fed into the sheet feeding unit in a predetermined direction. A transport mechanism for transporting, a feed roller that is disposed between the transport mechanism and the sheet feeding unit, and feeds the sheet medium fed into the sheet feeding unit toward the transport mechanism, and an outer peripheral surface of the feed roller; A separation roller that rotates in the opposite direction when two or more sheet media exist between the feed roller and the same direction as the feed roller. And a separation mechanism including.

  In addition, the ticket separating and transporting mechanism according to the above-mentioned Japanese Patent Application Laid-Open No. 2003-242530 separates the sheet detection unit that detects the number of all the inserted tickets and the tickets that have passed through the sheet detection unit one by one. And a control unit that drives and controls the separation unit according to the number of sheets detected by the sheet number detection unit and changes the method of separating the tickets in the separation unit according to the number of tickets. The separating unit includes a first roller disposed on one side of a conveyance path through which tickets are conveyed, and a second roller facing the first roller on the other side of the conveyance path, The control unit rotates the first and second rollers along the transport direction of the bills when the bills detected by the number detection unit are passed between the first and second rollers. The tickets that are detected by the number detection unit to be in a stacked state When passing between over La, but also including those configured to rotate along the first roller in the conveying direction so as to reverse rotate the second roller.

  By the way, the problem to be solved by the present invention is to prevent the occurrence of malfunction such as failure of following the separation roll for separating the recording sheets one by one, and also due to the malfunction of the separation roll. An object of the present invention is to provide a sheet feeding device capable of preventing jamming of a recording sheet and suppressing uneven wear when a friction coefficient on the surface of a separation roll is lowered, and an image forming apparatus using the same.

That is, the invention described in claim 1 is a delivery roll for feeding a plurality of stacked recording sheets;
Among the recording sheets sent out by the sending roll, a transport roll that transports only one recording sheet on the front side;
When two or more recording sheets are sent out by the delivery roll and are in contact with the transport roll, the second or more recording sheets positioned on the back side are referred to as the first recording sheet. A separation roll to separate;
A separation roll rotation detecting means for detecting a rotation state of the separation roll;
And a determination unit that determines whether or not the recording sheet is normally separated according to a detection result of the separation roll rotation detection unit.

  The invention described in claim 2 further comprises warning means for issuing a warning when the determination means detects that the recording sheet is not normally separated. The sheet feeding device described in 1. above.

Furthermore, the invention described in claim 3 is a rotational torque control means for controlling a rotational torque applied to the separation roll;
A sheet number detecting means for detecting the number of recording sheets fed by the feeding roll;
3. The sheet feeding device according to claim 1, further comprising a control unit configured to control a rotation torque applied to the separation roll by the rotation torque control unit in accordance with a detection result of the sheet number detection unit. It is.

  According to a fourth aspect of the present invention, the control means includes a control means for controlling a rotational torque applied to the separation roll by the rotational torque control means in accordance with a detection result of the separation roll rotation detection means. The sheet feeding device according to claim 1, further comprising a sheet feeding device.

Furthermore, the invention described in claim 5 is a delivery roll for sending out a plurality of laminated recording sheets;
Among the recording sheets sent out by the sending roll, a transport roll that transports only one recording sheet on the front side;
When two or more recording sheets are sent out by the delivery roll and are in contact with the transport roll, the second or more recording sheets positioned on the back side are referred to as the first recording sheet. A separation roll to separate;
Separation roll rotation detecting means for detecting the rotation state of the separation roll;
A determination unit that determines whether or not the recording sheet has been normally separated according to a detection result of the separation roll rotation detection unit;
An image forming apparatus comprising: an image forming unit that forms an image on a recording sheet that is fed by the feed roll and transported in a state of being separated by the transport roll and the separation roll. Device.

  According to the first aspect of the invention, the separation roll for separating the recording sheets one by one by detecting the rotation state of the separation roll and determining whether the recording sheets have been normally separated. It is possible to immediately detect that an operation failure such as a follow-up failure has occurred, and to prevent the recording sheet from jamming due to the operation failure of the separation roll.

  Further, according to the invention described in claim 2, it is possible to immediately detect the occurrence of an operation failure such as a follow-up failure for separating the recording sheets one by one, and issue a warning. The user can respond appropriately.

  Furthermore, according to the invention described in claim 3, when the recording sheet is double-fed or the like, the separation for separating the recording sheets one by one is controlled by controlling the rotational torque applied to the separation roll. Prevents the occurrence of malfunctions such as following failure of the roll, and also prevents jamming of the recording sheet due to the malfunction of the separation roll, and uneven wear when the friction coefficient on the surface of the separation roll decreases. Can be suppressed.

  According to the invention described in claim 4, when the recording sheets are double-fed, etc., the separation for separating the recording sheets one by one is controlled by controlling the rotational torque applied to the separation roll. Prevents the occurrence of malfunctions such as following failure of the roll, and also prevents jamming of the recording sheet due to the malfunction of the separation roll, and uneven wear when the friction coefficient on the surface of the separation roll decreases. Can be suppressed.

  Furthermore, according to the fifth aspect of the present invention, it is possible to prevent double feeding and jamming of the recording sheets, and it is possible to always form a good image on the recording sheets.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 shows a tandem type digital color printer as an image forming apparatus to which the paper feeding device according to the first embodiment of the present invention is applied. FIG. 3 shows a tandem type digital color copying machine as an image forming apparatus to which the paper feeding apparatus according to Embodiment 1 of the present invention is applied.

  2 and 3, reference numeral 1 denotes a main body of a tandem type digital color printer and copying machine. In the case of a digital color copying machine, as shown in FIG. An automatic document feeder (ADF) 3 that automatically conveys the documents one by one and a document reading device 4 that reads an image of the document 2 conveyed by the automatic document feeder 3 are provided. The document reader 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 from a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. The image reading element 11 composed of a CCD or the like is scanned and exposed through a reduction optical system, and the color material reflected light image of the document 2 is formed at a predetermined dot density (for example, 16 dots / mm) by the image reading element 11. It is supposed to read.

  The reflected light image of the document 2 read by the document reading device 4 is, for example, image processing device 12 as document reflectance data of three colors of red (R), green (G), and blue (B) (each 8 bits). The image processing apparatus 12 performs predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color / moving editing, etc., on the reflectance data of the document 2. Is given. Further, the image processing device 12 performs predetermined image processing on image data sent from a personal computer or the like.

  Then, the image data that has been subjected to the predetermined image processing by the image processing device 12 as described above is similarly processed by the image processing device 12 to yellow (Y), magenta (M), cyan (C), black (K) (each 8-bit) gradation data of four colors, and as described below, yellow (Y), magenta (M), cyan (C), and black (K) image forming units 13Y, 13M, and 13C. The image exposure device 14 performs image exposure with the laser beam LB in accordance with gradation data of a predetermined color.

  By the way, inside the tandem type digital color printer and copying machine main body 1, as shown in FIGS. 2 and 3, yellow (Y), magenta (M), cyan (C), black (K) 4. The two image forming units 13Y, 13M, 13C, and 13K are arranged in parallel at regular intervals in the horizontal direction. The image forming units 13Y, 13M, 13C, and 13K, together with a transfer unit 22 described later, constitute an image forming unit that forms an image on a recording sheet fed from a paper feeding device. The image forming unit may be a monochrome or four-cycle image forming unit provided with a single photosensitive drum, and is not limited to the electrophotographic method, but may be other image forming methods such as an inkjet method. An image may be formed on a recording sheet.

  These four image forming units 13Y, 13M, 13C, and 13K are all configured in the same manner, and roughly divided, a photosensitive drum 15 as an image carrier that is rotationally driven at a predetermined speed, and the photosensitive drum. A charging roll 16 for primary charging that uniformly charges the surface of 15, an image exposure device 14 that exposes an image corresponding to a predetermined color on the surface of the photosensitive drum 15, and forms an electrostatic latent image; A developing unit 17 that develops the electrostatic latent image formed on the photosensitive drum 15 with toner of a predetermined color and a cleaning device 18 that cleans the surface of the photosensitive drum 15 are configured. These photosensitive drums 15 and image forming members disposed in the periphery are integrally unitized, and are configured to be individually replaceable from the printer and the copying machine main body 1.

  As shown in FIGS. 2 and 3, the image exposure apparatus 14 is configured in common to the four image forming units 13Y, 13M, 13C, and 13K, and uses four semiconductor lasers (not shown) to reproduce original color materials for each color. The laser light LB-Y, LB-M, LB-C, and LB-K are emitted from these semiconductor lasers in accordance with the gradation data after being modulated in accordance with the gradation data. Of course, the image exposure device 14 may be individually configured for each of a plurality of image forming units. The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the semiconductor laser are irradiated to the polygon mirror 19 through an f-θ lens (not shown), and are deflected and scanned by the polygon mirror 19. The The laser beams LB-Y, LB-M, LB-C, and LB-K deflected and scanned by the polygon mirror 19 are exposed to exposure points on the photosensitive drum 15 through an imaging lens and a plurality of mirrors (not shown). Then, scanning exposure is performed obliquely from below.

  As shown in FIG. 2, the image exposure device 14 scans and exposes an image on the photosensitive drum 15 from below, so that the image exposure device 14 includes four image forming units 13Y located above. , 13M, 13C, 13K, etc., the toner may fall and be contaminated. Therefore, the periphery of the image exposure device 14 is sealed by a rectangular parallelepiped frame 20, and four laser beams LB-Y, LB-M, LB-C, and LB- are formed on the upper portion of the frame 20. Transparent glass windows 21Y, 21M, 21C, and 21K as shield members are provided to expose K on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K.

  From the image exposure device 12, an image exposure device provided in common for the image forming units 13Y, 13M, 13C, and 13K of each color of yellow (Y), magenta (M), cyan (C), and black (K). 14, the image data of each color is sequentially output, and the laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the image exposure device 14 in accordance with the image data are supplied to the corresponding photosensitive drums. The surface of 15 is scanned and exposed to form an electrostatic latent image. The electrostatic latent images formed on the photosensitive drum 15 are respectively developed in yellow (Y), magenta (M), cyan (C), and black (K) colors by developing units 17Y, 17M, 17C, and 17K. Developed as a toner image.

The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K are as follows. On the intermediate transfer belt 25 of the transfer unit 22 arranged over the image forming units 13Y, 13M, 13C, and 13K, the images are transferred in multiple by the four primary transfer rolls 26Y, 26M, 26C, and 26K. These primary transfer rolls 26Y, 26M, 26C, and 26K are disposed on the back side of the intermediate transfer belt 25 corresponding to the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K. The primary transfer rolls 26Y, 26M, 26C, and 26K in this embodiment use volume resistance values that have been adjusted to a resistance of 10 ⁵ to 10 ⁸ Ωcm. The primary transfer rolls 26Y, 26M, 26C, and 26K are connected to a transfer bias power source (not shown), and a transfer bias having a polarity opposite to a predetermined toner polarity (positive polarity in the present embodiment) is predetermined. It is applied at the timing.

Further, as shown in FIG. 2, the intermediate transfer belt 25 is wound around the drive roll 27, the tension roll 24, and the backup roll 28 with a certain tension, and has excellent constant speed (not shown). The drive roll 27 is rotationally driven by a dedicated drive motor and is circulated at a predetermined speed in the direction of the arrow. The intermediate transfer belt 25 is made of, for example, a belt material (rubber or resin) that does not cause charge-up, and its volume resistance value is adjusted to a resistance of about 10 ⁵ to 10 ¹² Ωcm. Has been.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 25 are pressed against the backup roll 28 as shown in FIG. The recording sheet 30 that has been secondarily transferred onto the recording sheet 30 as a recording sheet by the pressing force and electric field by the secondary transfer roll 29 is transferred to the fixing device 31 positioned above. It is conveyed. The secondary transfer roll 29 is in pressure contact with the side of the backup roll 28, and secondary-transfers each color toner image onto a recording paper 30 conveyed upward from below. The recording paper 30 onto which the toner images of the respective colors are transferred is subjected to a fixing process by heat and pressure by a fixing device 31 and then discharged onto a discharge tray 33 provided on the upper portion of the main body 1 by a discharge roll 32. The

  As shown in FIGS. 2 and 3, the recording paper 30 is of a predetermined size and material from the paper feed tray 34 as one component of the paper feeding device, as will be described later. The paper is fed by the feed roll 36a and the retard roll 36b for separation and conveyance, and is once conveyed to the registration roll 38 via the paper conveyance path 37 provided with the conveyance roll 37a and stopped. A transport path 37 of the fed recording paper 30 is directed upward in the vertical direction. The recording paper 30 supplied from the paper feed tray 34 is sent to the secondary transfer position of the intermediate transfer belt 25 by a registration roll 38 that rotates at a predetermined timing.

  In the above digital color printer and copying machine, when making a full-color double-sided copy, the recording paper 30 having an image fixed on one side is not directly discharged onto the discharge tray 33 by the discharge roll 32, but is shown in the figure. The conveyance direction is switched by the switching gate not to be conveyed, and the sheet is conveyed to the duplex conveyance unit 40 via the sheet conveyance roller pair 39. In the double-sided conveyance unit 40, the recording paper 30 is conveyed to the registration roll 38 again with the front and back sides of the recording paper 30 reversed by the conveyance roller pairs 45 and 46 provided along the conveyance path 41. This time, after the image is transferred and fixed on the back surface of the recording paper 30, it is discharged onto the discharge tray 33.

  In FIGS. 2 and 3, 44Y, 44M, 44C, and 44K supply toners of predetermined colors to the developing units 17 of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Each toner cartridge is shown.

  FIG. 4 shows the image forming units of the digital color printer and the copying machine.

  The four image forming units 13Y, 13M, 13C, and 13K of yellow, magenta, cyan, and black are all configured in the same manner as shown in FIG. 4, and these four image forming units. In 13Y, 13M, 13C, and 13K, as described above, yellow, magenta, cyan, and black toner images are sequentially formed at predetermined timings, respectively. As described above, the image forming units 13Y, 13M, 13C, and 13K for the respective colors are provided with the photosensitive drums 15, and the surfaces of these photosensitive drums 15 are uniformly formed by the charging rolls 16 for primary charging. Charged. Thereafter, the surface of the photosensitive drum 15 is scanned and exposed to an image forming laser beam LB emitted from the image exposure device 14 according to the image data, and an electrostatic latent image corresponding to each color is formed. The laser beam LB that is scanned and exposed on the photosensitive drum 15 is set so as to be exposed from an obliquely lower side slightly to the right of the photosensitive drum 15. The electrostatic latent image formed on the photosensitive drum 15 is yellow, magenta, cyan, and black by the developing roll 17a of the developing unit 17 of each image forming unit 13Y, 13M, 13C, and 13K. The visible toner images are developed with the toners of the toner, and the visible toner images are sequentially transferred in multiple onto the intermediate transfer belt 25 by the charging of the primary transfer roll 26.

  Residual toner, paper dust, and the like are removed from the surface of the photosensitive drum 15 after the toner image transfer process by the cleaning device 18 to prepare for the next image forming process. The cleaning device 18 includes a cleaning blade 42, and the cleaning blade 42 removes residual toner, paper dust, and the like on the photosensitive drum 15. Further, the surface of the intermediate transfer belt 25 after the toner image transfer process is finished, as shown in FIGS. 2 and 3, the residual toner and paper dust are removed by the cleaning device 43, and the next image forming process. Prepare for. The cleaning device 43 includes a cleaning brush 43a and a cleaning blade 43b. The cleaning brush 43a and the blade 42 remove residual toner, paper dust, and the like on the intermediate transfer belt 25.

  As shown in FIG. 2, the printer main body 1 has a manual feed tray 47 on the left side surface. By rotating the manual feed tray 47 counterclockwise to a substantially horizontal position, the printer main body 1 is stopped. From the manual feed tray 47, recording sheets of different materials and sizes such as OHP sheets and postcards can be fed via the feed roll 48 and the retard pad 49.

  FIG. 5 is a plan view showing the paper feed tray of the paper feed device used in the laser printer, and FIG. 6 is a cross-sectional view showing the paper feed tray.

  As shown in FIG. 7, one sheet feeding device 50 is disposed at the lowermost stage inside the laser printer body 1 that also serves as the sheet feeding device body, and at the bottom of the laser printer body 1, A plurality of sheet feeding devices 51 to 53 that can be arbitrarily added as an option are arranged. The paper feeding devices 50 to 53 include a paper feeding tray 34 as shown in FIG. 5, and the paper feeding tray 34 is located on the front side of the laser printer main body 1 (in the direction perpendicular to the drawing in FIG. 7). It can be withdrawn.

  As shown in FIGS. 5 and 6, the paper feed tray 34 is formed in a substantially rectangular box shape with an open top surface, and the paper feed tray 34 is disposed on the front side of the paper feed tray 34. A front panel 54 that also serves as a handle for pulling out from 1 is provided. As shown in FIG. 5, the paper feed tray 34 is configured to feed the recording paper 30 to the printer body 1 in a direction orthogonal to the attaching / detaching direction, in the illustrated example, in the left direction in the figure. The recording paper 30 is accommodated inside the paper feed tray 34 with the one end 34a on the near side as a reference. The paper feed tray 34 adjusts the positions of the side guide member 55 that guides the side of the paper 30 and the rear guide member 56 that guides the back according to the size of the recording paper 30 to be accommodated. As a result, it is a so-called “universal cassette” that can accommodate paper from a maximum A3 size paper to a minimum 5.5 inch paper.

  Further, as shown in FIG. 6, a bottom plate 57 as a paper support member for placing a large number (a plurality of) of recording papers 30 is tiltably provided inside the paper feed tray 34. Yes. The bottom plate 57 has a rear end portion 57 a rotatably attached to the paper feed tray 34, and a front end portion 57 b that can be raised and lowered from the bottom portion of the paper feed tray 34 to the upper end portion in the height direction. Yes. Further, as shown in FIGS. 5 and 6, a push-up lever 58 (push-up member) that pushes up the bottom plate 57 is disposed inside the paper feed tray 34 below the front end side of the bottom plate 57. The push-up lever 58 is rotatably attached to the bottom of the paper feed tray 34 as shown in FIG. The bottom plate 57 is appropriately provided with notches so as not to hinder the movement of the side guide member 55 and the rear guide member 56.

  As shown in FIG. 5, the push-up lever 58 protrudes from the shaft member 59 that is rotated by a drive mechanism 63 provided on the end surface on the back side of the paper feed tray 34 so as to be orthogonal to the shaft member 59. It is composed of three arm members 60, 61, 62 provided.

  The push-up lever 58 is rotated by rotationally driving the shaft member 59 by the drive mechanism 63, and pushes up the lower surface of the bottom plate 57 by the tip portions of the arm members 60, 61, 62, and on the bottom plate 57. The upper surface of the loaded recording paper 30 is pressed against the nudger roll 35 and fed. In addition, illustration of the bottom plate 57 is abbreviate | omitted in FIG.

  By the way, the paper feeding device according to this embodiment transports only one recording sheet on the front side among the recording rolls that send out a plurality of stacked recording sheets and the recording sheets that are sent out by the sending rolls. When two or more recording sheets are sent out by the conveying roll and in contact with the conveying roll, and the two or more recording sheets are sent out by the sending roll, A separation roll separating from the recording sheet, a separation roll rotation detecting means for detecting a rotation state of the separation roll, and whether the recording sheet has been normally separated according to a rotation detection result of the separation roll rotation detection means. Determination means for determining whether or not.

  Further, in this embodiment, the sheet number detection means includes a separation roll driving unit that rotationally drives the separation roll in a predetermined direction, and a sheet number detection unit that detects the number of recording sheets fed by the feeding roll. The rotation direction of the separation roll by the driving means is controlled according to the detection result.

  That is, the paper feeding device 50 according to this embodiment includes an inside of the printer main body 1 that also serves as the paper feeding device main body, as shown in FIGS. The upper part feeds a nudger roll 35 as a delivery roll for sending out the recording paper 30 stored in the paper feed tray 34 and the recording paper 30 fed by the nudger roll 35 one by one. Of the recording paper 30 sent out by the nudger roll 35, as a result, a feed roll 36a as a transport roll for transporting only one recording paper 30 on the front surface side, and abutting or pressure contact with the feed roll 36a. When two or more recording papers 30 are sent out by the feed roll 36a, the second or more recording papers 30 positioned on the back side are moved to the first sheet. A retard roller 36b as separating roller for separating the recording sheet 30 is disposed.

  As shown in FIG. 5, the nudger roll 35 is one end on the near side as a reference of the paper feed tray 34 so that paper can be fed from the small size recording paper 30 to the large size recording paper 30. It is disposed near the tip 34a near the portion 34a and in the paper feeding direction.

  The nudger roll 35, the feed roll 36a and the retard roll 36b are, for example, a synthetic resin roll-shaped member attached to a metal shaft, and a rubber coating layer coated on the outer peripheral surface of the roll-shaped member. As shown in FIG. 1, two are arranged at a predetermined interval along a direction orthogonal to the paper feeding direction (sheet conveying direction). Of course, all of the nudger roll 35, the feed roll 36a and the retard roll 36b may be formed of rubber rolls. These nudger roll 35, feed roll 36a, and retard roll 36b are, for example, as shown in FIG. 8, the free ends of cantilevered rotary shafts 75, 83, 91 whose base end side is rotatably supported. It is attached in the vicinity, and is detachably attached to the rotary shafts 75, 83, 91 by a snap fit 76.

  In FIG. 8, for the sake of convenience, the arrangement of the nudger roll 35, the feed roll 36a, and the retard roll 36b and the feeding direction of the recording paper 30 are set in the opposite directions to those in FIG. 35, the arrangement of the feed roll 36a and the retard roll 36b and the feeding direction of the recording paper 30 may be set as appropriate.

  For example, as shown in FIG. 1, the nudger roll 35 is attached in the vicinity of the free end of a cantilevered rotating shaft 75 (see FIG. 8) whose base end portion is rotatably supported. The rotary shaft 75 is detachably attached by a snap fit 76 described later. As shown in FIG. 9, a concave groove 77 is formed at the tip of the rotating shaft 75, and a flange 78 made of synthetic resin such as the nudger roll 35 is provided with a claw 79 along the axial direction. The projection 70 of the claw portion 79 protruding from the flange 78 of the nudger roll 35 or the like is configured to be fitted into the concave groove 77 of the rotating shaft 75. Then, the snap fit 76 is released by lifting the projection 80 of the claw portion 79 projecting from the flange 78 such as the nudger roll 35 with the fingertip to remove it from the concave groove 77 of the rotating shaft 75, thereby releasing the nudger roll 35. Etc. can be exchanged.

  As shown in FIG. 1, the rotating shaft 75 to which the nudger roll 35 is attached has a base end side attached to a swing frame 81, and the swing frame 81 is provided at one end thereof. The swinging angle is regulated by the regulating member 81a. The swing frame 81 is swingably mounted around the rotation shaft 83 of the feed roll 36a, and the nudger roll 35 is recorded on the paper feed tray 34 by a coil spring 84 shown in FIG. It is urged so as to come into pressure contact with the paper 30.

  Further, as shown in FIG. 1, the feed roll 36a is connected to a driven gear 85 via a driven gear 85 attached to an end of a rotating shaft 83 that is rotatably supported by a swing frame 81 of the paper feeding device. A first drive motor 87 to which a drive gear 86 that meshes with 85 is attached is configured to be rotationally driven at a predetermined timing and at a predetermined rotation speed.

  Further, as shown in FIG. 1, the nudger roll 35 is connected to the other end of the rotating shaft 83 of the feed roll 36a by a transmission gear 88 fixedly attached to the nudger roll 35 via an intermediate gear 89. A rotational driving force is transmitted to a driven gear 89 provided on the rotating shaft 75, and is driven to rotate at a predetermined rotational speed at the same timing as the feed roll 36a.

  Further, as shown in FIG. 1, the retard roll 36b is driven by a driven gear 91 attached to an end of a rotating shaft 75 that is rotatably supported by a support frame 82 of the sheet feeding device. A drive motor 93 for a retard roll as a second drive motor to which a drive gear 92 that meshes with the gear 91 is attached is configured to apply a rotational torque at a predetermined timing and in a predetermined rotation direction.

  The rotational torque applied to the retard roll 36b by the retard roll drive motor 93 is set so as to be appropriately controlled by the control means described later. This retard roll drive motor 93 is connected to the feed roll 36a before the recording sheet 30 enters the retard roll 36b or when the number of sheets is detected by the sheet number detecting means described later. The rotation direction is set to be the same, and after the recording sheet 30 enters the retard roll 36b, the rotation torque is set in the direction opposite to that of the feed roll 36a.

  In FIG. 8, S indicates a contact type sensor for detecting the presence or absence of paper.

  The first drive motor 87 is rotationally driven in a predetermined direction (paper feeding direction), whereby the feed roll 36a is rotationally driven as shown in FIGS. 1 and 8, and the feed roll 36 The nudger roll 35 is also rotationally driven via 36a.

  Further, as shown in FIG. 1, the retard roll 36b is urged so as to be swingable in a direction in which the feed roll 36a is brought into contact with and separated from the support frame 82 of the sheet feeding device and to be in pressure contact with the feed roll 36a. The rotating shaft 91 is attached. For example, a predetermined torque is applied to the retard roll 36b in a direction opposite to the paper feeding direction by a second drive motor 93 at a predetermined timing, and the recording paper 30 is 1 by the retard roll 36b and the feed roll 36a. It is configured to feed paper in a state where it is picked up one by one.

  Further, as shown in FIG. 1, a sheet number detecting means 94 as a number detecting means for detecting the number of recording sheets 30 fed by the nudger roll 35 is disposed on the side of the retard roll 36a. Yes. The sheet number detection means 94 includes a detection lever 94a as an actuator that comes into contact with the recording paper 30 fed by the nudger roll 35, and a detection unit comprising an optical sensor or the like for detecting the rotation (tilt) angle of the detection lever 94a. By detecting with 94b, the number of recording sheets 30 such as whether the recording sheet 30 sent out by the nudger roll 35 is one sheet or two sheets or more is detected.

  In addition, the detection lever 94a of the sheet number detection means 94 normally contacts a detected plate 94c disposed horizontally at the upper end of the recording paper 30 in the paper feeding direction, as shown in FIGS. When the recording paper 30 that has stopped in contact and is fed out by the nudger roll 35 passes between the upper end of the detection lever 94a and the detected plate 94c, the thickness of the recording paper 30 is reduced. Accordingly, the recording lever 30 is pushed down by the corresponding amount and rotated, and the amount of rotation of the detection lever 94a is enlarged by the lever principle and detected by the detection unit 94b, and the recording paper 30 fed out by the nudger roll 35 is one sheet. It is possible to detect the number of recording sheets 30 with high accuracy, such as whether the number is two or more. Note that the information regarding the thickness of the recording sheet, whether the recording paper 30 is plain paper, thin paper, or thick paper, is known based on information from the user interface or the paper feed tray 34, so the recording paper 30 Even if the paper is thin paper or thick paper other than plain paper, it can be detected with high accuracy.

  As described above, the sheet number detecting means 94 is not limited to a contact type equipped with a detection lever, but an ultrasonic type that detects the number of recording sheets 30 fed by the feed roll 36a by ultrasonic waves. Of course, it is also possible to use a light transmission type that detects the number of recording sheets 30 fed by the feed roll 36a by the amount of light transmission.

  The second drive motor 93 that rotationally drives the retard roll 36b detects at least one rotational state such as the rotational direction and rotational amount (including rotational speed) or rotational torque of the retard roller 36b. A retard roller rotation sensor 95 is attached as a separating roll rotation detecting means. As the retard roller rotation sensor 95, for example, a rotation encoder or the like is used. As the retard roller rotation sensor 95, any other sensor can be used as long as it can detect at least the rotation direction of the retard roller 36b. Of course, it may be used.

  Further, the retard roller driving motor 93, the sheet number detecting means 94, and the retard roller rotation sensor 95 are connected to a control circuit 100 as shown in FIG. 1, and the control circuit 100 detects the number of sheets. In accordance with detection signals output from the means 94 and the retard roller rotation sensor 95, the rotation direction of the retard roll 36b by the drive motor 93 for the retard roll is controlled.

  FIG. 10 is a block diagram illustrating a printer control circuit that also serves as the control circuit 100 of the paper feeding device 50.

  In FIG. 10, reference numeral 100 denotes a control circuit having a function as a control means for controlling the paper feeding device and a rotational torque control means. This control circuit 100 is a ROM for storing programs, predetermined parameters, and the like. A storage unit 101 including a RAM or the like and a calculation unit 102 including a CPU or the like that performs calculation and control processing based on a program stored in the storage unit 101, predetermined parameters, and the like are provided.

  The control circuit 100 is connected to a user interface 103 for instructing the type of recording sheet to be printed, the number of prints, and the like. The user interface 103 issues a warning when an abnormality occurs in the paper feeding device 50. It also has a function as warning means for issuing a warning by displaying a message or the like to the user.

  Further, the control circuit 100 is supplied with detection signals from the sheet number detecting means 94 and the retard roll rotation sensor 95 of the sheet feeding device 50 and is connected with a drive motor 93 for the retard roll. The rotational torque of the roll drive motor 93 is controlled by the control circuit 100.

  In the configuration described above, the paper feeding device according to this embodiment prevents the occurrence of malfunctions such as the following failure of the separation roll for separating the recording sheets one by one as follows. Thus, it is possible to prevent jamming of the recording sheet due to the malfunction of the separation roll, and to suppress uneven wear when the friction coefficient on the surface of the separation roll is reduced.

  That is, in the paper feeder 50 according to this embodiment, as shown in FIGS. 1 and 10, the nudger roll 35 is rotationally driven by rotating the first drive motor 87 at a predetermined timing. Of the recording sheets 30 stacked on the paper feed tray 34, only the uppermost recording sheet 30 or about one to two sheets of the uppermost recording sheet 30 and the recording sheet 30 positioned therebelow. Paper is fed. At that time, when the leading edge of the recording paper 30 fed by the nudger roll 35 comes into contact with the upper feed roll 36a, a plurality of recording papers 30 are fed or a jam of the recording paper 30 occurs. As shown in FIG. 12A, the recording paper 30 fed by the nudger roll 35 is set so that the leading edge is fed toward the lower retard roll 36b. Yes.

  At this time, in the paper feeding device 50, the retard roll 36b feeds only the uppermost recording paper 30 by separating the recording paper 30 fed two or more sheets, and the retard roll driving motor 93 is driven by the retard roll 36b. Thus, a rotational torque is applied in the direction of separating the recording paper 30 fed two or more sheets, that is, in the clockwise direction in the figure, but when the retard roll 36b is driven to rotate in the clockwise direction in the figure, the nudger As shown in FIG. 12B, the leading edge of the recording paper 30 fed by the roll 35 is buckled by being brought into contact with the surface of the retard roll 36b and pushed back, and the recording paper 30 is jammed. There has been drowning in the past.

  In the paper feeder 50, as shown in FIGS. 1 and 10, since the nudger roll 35 is always in contact with the surface of the recording paper 30, it is added to the recording paper 30 during long-term use. It is known that additives such as kaolin adhere to and accumulate on the surface of the nudger roll 35 and the friction coefficient on the surface of the nudger roll 35 decreases.

  Then, in the paper feeder 50, as shown in FIG. 12C, the retard roll 36b that contacts the nudger roll 35 slips, and so-called uneven wear in which only a part of the surface of the retard roll 36b is worn. It has been conventionally known that this occurs.

  Therefore, in the sheet feeding device 50 according to this embodiment, as shown in FIG. 10, a CPU (not shown) of the control circuit 100 responds to a detection signal from the sheet number detection means 94 as shown in FIG. It is determined whether the number of fed recording sheets 30 is 1 or less (0 or 1) or 2 or more (step 101), and the control circuit 100 determines that the number of fed recording sheets 30 is 1. If it is determined that the number of sheets is equal to or less than 0 (0 or 1), the rotation direction of the retard roll 36b is changed according to the detection signal from the retard roll rotation sensor 95 by switching the rotational torque by the drive motor 93 for the retard roll. It is determined whether the rotation direction is normal (in the illustrated example, the counterclockwise direction) and the rotation speed is 80% or more of a predetermined value (step 102).

  As shown in FIG. 1, the rotational speed of the retard roll 36b is controlled by a retard roll drive motor 93. The rotational speed of the feed roll 36a is recorded in the retard roll 36b as shown in FIG. It is transmitted through the paper 30 and a rotational force in the same direction as the rotational direction of the feed roll 36a acts.

  At this time, in FIG. 14, assuming that the moving speed of the feed roll 36a is A, the moving speed of the recording paper 30 is B, and the moving speed of the retard roll 36b is C, in the normal state, the relationship of A> B> C is satisfied. In addition, the rotational speed of the retard roll 36b is set so that the moving speed C of the retard roll 36b is about 10% slower than the moving speed A of the feed roll 36a.

  For example, as shown in FIG. 15, the rotational speed of the retard roll 36b is not gradually increased to a predetermined rotational speed at the time of rising and falling, but is gradually decreased to a predetermined rotational speed. It is set so as to increase to a speed or gradually decrease from a predetermined rotational speed, and is configured so that the retard roll 36b can be driven smoothly.

  However, as described above, when slip or the like occurs in the feed roll 36a, the rotation direction of the retard roll 36b is not the normal rotation direction (in the illustrated example, the counterclockwise direction), The rotational speed of the retard roll 36b may be less than 80% of the predetermined value.

  Therefore, in this embodiment, the control circuit 100 determines that the rotation direction of the retard roll 36b is the normal rotation direction (counterclockwise direction in the illustrated example) in accordance with the detection signal from the retard roll rotation sensor 95. In addition, it is determined whether or not the rotational speed is 80% or more of the predetermined value (step 102), and the rotational direction of the retard roll 36b is not the normal rotational direction, or the rotational speed is less than 80% of the predetermined value. If it is determined that there is a signal, a signal is sent to the retard roll drive motor 93 to decrease the reverse rotation speed by a predetermined value ΔT (step 103), and then the process returns to step 101.

  The control circuit 100 again determines that the rotation direction of the retard roll 36b is a normal rotation direction (counterclockwise direction in the illustrated example) in response to the detection signal from the retard roll rotation sensor 95. Further, it is determined whether or not the rotation speed is 80% or more of a predetermined value (step 102), and it is determined that the rotation direction of the retard roll 36b is a normal rotation direction and the rotation speed is 80% or more of the predetermined value. Then, it is determined whether or not the paper feeding operation is finished, that is, whether or not to feed the second and subsequent sheets (step 104). If the paper feeding operation is not finished, the process returns to step 101 and the paper feeding operation is performed. If it is finished, the paper feeding operation is finished.

  On the other hand, when the control circuit 100 determines that the number of fed recording sheets 30 is two or more (multiple feeding has occurred) in response to the detection signal from the sheet number detecting means 94 (step 101). ) In response to the detection signal from the retard roll rotation sensor 95, it is determined whether or not the rotation direction of the retard roll 36b is the reverse rotation direction (clockwise direction) (step 105), and the rotation direction of the retard roll 36b is reverse rotation. In the case of the direction, since the recording paper 30 fed by two or more sheets can be separated by the feed roll 36a and the retard roll 36b, the paper feeding operation is continued and whether or not the paper feeding operation is finished. Determination is made (step 104).

  On the other hand, when the rotation direction of the retard roll 36b is not the reverse rotation direction (clockwise direction in the illustrated example), the control circuit 100 sends a signal to the drive motor 93 for the retard roll, After increasing the reverse speed by a predetermined value ΔT2 (step 106), the process returns to step 101.

  Here, the predetermined value ΔT2 for increasing the reverse rotation speed may be the same value as the predetermined value ΔT1, or may be set to a different value. Further, the predetermined values ΔT1 and ΔT2 may be configured to be appropriately changed by using a user interface 103 (not shown) of the control circuit 100 or the like.

  The control circuit 100 determines that the rotation direction of the retard roll 36b is the normal rotation direction (counterclockwise in the illustrated example) although the number of fed recording sheets 30 is two or more (step 101). (Step 105), the recording paper 30 fed two or more sheets can be separated by the feed roll 36a and the retard roll 36b. It is determined whether or not the paper operation is finished (step 104).

  Here, when the leading edge of the recording paper 30 is pushed back by being brought into contact with the surface of the retard roll 36b as shown in FIG. If the number of fed recording sheets 30 is one or less (step 101), it is determined whether or not the rotation direction of the retard roll 36b is a normal rotation direction (counterclockwise direction in the illustrated example). If the rotation direction is not the normal rotation direction (step 102), the reverse rotation speed is decreased by ΔT1, and the leading edge of the recording paper 30 is fed in the normal rotation direction by the retard roll 36b. The occurrence of buckling at the tip of 30 can be avoided.

FIG. 1 is a perspective configuration diagram showing a sheet feeding device according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a tandem type full-color printer as an image forming apparatus to which the paper feeding device according to Embodiment 1 of the present invention is applied. FIG. 3 is a block diagram showing a tandem type full-color copying machine as an image forming apparatus to which the paper feeding device according to the first embodiment of the present invention is applied. FIG. 4 is a block diagram showing an image forming unit of a tandem type full-color printer as an image forming apparatus to which the sheet feeding device according to Embodiment 1 of the present invention is applied. FIG. 5 is a plan view showing the paper feed tray. FIG. 6 is a cross-sectional configuration diagram showing the paper feed tray. FIG. 7 is a block diagram showing a tandem type full-color printer as an image forming apparatus provided with a plurality of sheet feeding devices according to Embodiment 1 of the present invention. FIG. 8 is a perspective configuration diagram showing the main part of the sheet feeding device according to Embodiment 1 of the present invention. FIG. 9 is a partially broken configuration diagram showing a roll mounting structure. FIG. 10 is a block diagram showing a control circuit of the printer. FIG. 11 is a configuration diagram illustrating a paper feeding unit of the printer. 12A to 12C are explanatory diagrams showing the paper feeding operation of the printer. FIG. 13 is a flowchart showing the operation of the sheet feeding device according to Embodiment 1 of the present invention. FIG. 14 is a schematic diagram showing the conveying force exerted on the paper. FIG. 15 is a graph showing a control state of the rotation speed of the paper feed roll.

Explanation of symbols

  34: paper feed tray, 30: recording paper, 35: nudger roll (delivery roll), 36a: feed roll (conveyance roll), 36b: retard roll (separation roll), 87: first drive motor, 93: first 2 drive motors, 95: retard roll rotation sensor, 100: control circuit.

Claims (5)

A delivery roll for sending out a plurality of laminated recording sheets;
Among the recording sheets sent out by the sending roll, a transport roll that transports only one recording sheet on the front side;
When two or more recording sheets are sent out by the delivery roll and are in contact with the transport roll, the second or more recording sheets positioned on the back side are referred to as the first recording sheet. A separation roll to separate;
A separation roll rotation detecting means for detecting a rotation state of the separation roll;
A sheet feeding device comprising: a determination unit that determines whether or not the recording sheet is normally separated according to a detection result of the separation roll rotation detection unit. The sheet feeding device according to claim 1, further comprising a warning unit that issues a warning when the determination unit detects that the recording sheet is not normally separated. Rotational torque control means for controlling rotational torque applied to the separation roll;
A sheet number detecting means for detecting the number of recording sheets fed by the feeding roll;
3. The sheet feeding device according to claim 1, further comprising a control unit configured to control a rotation torque applied to the separation roll by the rotation torque control unit in accordance with a detection result of the sheet number detection unit. . The said control means is provided with the control means which controls the rotational torque provided to the said separation roll by the said rotational torque control means according to the detection result of the separation roll rotation detection means. The paper feeder according to any one of the above. A delivery roll for sending out a plurality of laminated recording sheets;
Among the recording sheets sent out by the sending roll, a transport roll that transports only one recording sheet on the front side;
When two or more recording sheets are sent out by the delivery roll and are in contact with the transport roll, the second or more recording sheets positioned on the back side are referred to as the first recording sheet. A separation roll to separate;
Separation roll rotation detecting means for detecting the rotation state of the separation roll;
A determination unit that determines whether or not the recording sheet has been normally separated according to a detection result of the separation roll rotation detection unit;
An image forming apparatus comprising: an image forming unit that forms an image on a recording sheet that is fed by the feed roll and transported in a state of being separated by the transport roll and the separation roll. apparatus.

Images